In recent years, the number of mobile terminals that include various sensors is increasing. The mobile terminals can use the sensors to sense behaviors of users. The number of services using positional information as sensing information is increasing. For example, there is the following service. That is, the current position of a user is measured by a global positioning system (GPS) installed in a smart phone, a wireless local area network (LAN) or the like. When the user approaches a location (store, station or the like) specified by a service provider, a center server distributes, to a mobile terminal of the user, an application and coupon that can be used at the location. In the service, an application installed in the mobile terminal periodically acquires information of the current position of the mobile terminal from the GPS or the like and transmits the acquired positional information to the center server. The center server determines, on the basis of the received positional information, whether or not the user has entered in a range in which the service is provided. If the user is in the range, the center server distributes an application and recommended information.
For mobile terminals, there are multiple positioning methods such as autonomous navigation using a GPS, a wireless LAN, a public mobile phone line, an acceleration sensor and a geomagnetic sensor in order to acquire information of the positions of users. The amounts of power to be consumed by the mobile terminals and the accuracies of the positioning methods vary. In general, when a high-accuracy positioning method is used by a mobile terminal, the amount of power to be consumed by the mobile terminal is large. An application that uses positional information and is executed on a mobile terminal does not detect a range in which a service registered in the mobile terminal is provided. Thus, positional information is acquired using a high-accuracy positioning method at short time intervals and is continuously transmitted to the center server. When positioning is repeated with a high accuracy at short time intervals and positional information is transmitted to the center server, the center server can acquire detailed data of the position of a user. The mobile terminal, however, repeats positioning for a short time and consumes power. When an application of the mobile terminal executes positioning with a low accuracy, and the user is close to the range in which the service is provided, the mobile terminal is detected to be far from the range in which the service is provided. In this case, an application and recommended information may not be distributed. Even when the user is far from the range in which the service is provided, and positioning continues to be executed with a high accuracy, the mobile terminal consumes power.
Public mobile phone lines enable mobile terminals to perform communication upon subscriptions to the mobile terminals. Normally, the public mobile phone lines enable the mobile terminals to perform communication in order to receive calls and mails. A service for positioning mobile terminals through the public mobile phone lines is provided. Although the accuracy of the positioning is low, the amount of power to be consumed is small. If the positioning is to be executed with a high accuracy, the positioning is executed using a wireless LAN or a GPS and power is consumed in order to newly drive the sensor.
The following is a related-art document.
Japanese Laid-open Patent Publication No. 2006-115415 is an example of related art.